Stell frame cnc 1500X1000. Adjustable table your opinion please

After thinking that welding all the beams together, according to the previews plans i would have issues with the big weight, i decided to split the contruction into two , the bench and the CNC that will sit on that bench.
So i introduce the CNC pictures first
So i have the main frame
Attachment 11104

Then with the red color is the cutting table made by 80X80X5 beam
Attachment 11105

over the cutting table i will put aluminium profile tha will be bolted on the red cutting table. That profile has T slot for clamping item that will be cutted
Attachment 11106

And here we have some picures of the construction with all the items together
Attachment 11107Attachment 11108Attachment 11109Attachment 11110Attachment 11111Attachment 11112

if i want more depth for 3d cuts i will remove the cutting table(80mm) with the T slot( nearly 40mm) and i will put a 20mm mdf. That will give me about 100mm (80+40-20) more depth

I am waitting for your comments

Thanks

Vagelis

Nice. Looks great,

What size of the steel profile you decided on? If 80mm or bigger, you don't need the triangular plates. Believe me, will not move. Reason - the short profiles will hold it firm enough. If you insist, make them L shaped, so they will not bother you fitting longer than the table pieces.

And as for the size of profile, i am with Jonathan. Bigger the profile, the better. If resonance, its easier to drill a hole and fill it with something later.

I said it earlier some where but one of the best ways to fight resonance is avoiding perfect symmetry in the machine, meaning all pieces spaced same distance and mirrored exactly. Offsetting each piece even by 1cm here and there will have enormous impact. Same when avoiding mirroring

Quote:

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Originally Posted by silyavski

Nice. Looks great,

What size of the steel profile you decided on?

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At the above plans i use 80X80X5 beam for the red table and also for grey frame except the 4 lower beams that will have contact with the bench. Those four beams are 100X100X4. I think that the triangular pieces will help to achieve triangulation and parallelism and also stiffness.
I agree with you that if avoid symmetry and mirroring that will help to reduce resonance. As for the beam size i think even 80X80 or 100X100 will not have much difference to the final result.
The t-slot profiles are aluminium profiles that are used for for clamping solar panels at the roofs. I design the profile from a piece that i had.
I will come back with the gantry design. I will use one motor for X axis with double ballscrews and i may use double nut (preloaded with a spring) for each side
I want you opinion about this option. What kind o f spring is suitable for this use and where can I find it. I also would like to know what would be a good distance between Y and Z axis profiled rails ( i will use 20mm profiled rails ). Also what will be a good distance between the carriages of X axis ( outer side of carriages )

So far thanks everybody for the help

Vagelis

Hi Vagelis,

Looks ok to me. :thumsup: . . . Just a Couple of simple things that will help.

You could drop those inner triangle braces and just keep the inside corner ones but make them little larger, there will be more room with others gone. Not much gain strength wise from them being there and not having them means less welding which will lessen the chance of heat distortion.! . . . . Would do the same with corner braces for the Bed frame just to help keep it square.

Also the outer End triangles will be better placed on the outside of the box section and made larger so there is more contact area, they will also cover the ends of the section. Then when you weld just put short welds but on both edges. Again this lessens the chance of heat distortion by allowing short weld runs and balancing the welds pushing/pulling action.

Dean i made some corrections according to your advices. I am not sure i understood everything you said ( as my english are not excellent)
Let the photos talk

Attachment 11118Attachment 11117Attachment 11119Attachment 11115Attachment 11116
In order to go on with the plans, it would be good if somebody told me about Y and Z rails distances and distance between carriages of X axis. Finally i want your advice about X axis double preloaded ballnuts

Thanks

Vagelis

Hi Vagelis,

Normally people here on the forum use ball nuts and ballscrews bought from China. The most recommended vendors are Fred from BST Automation/aliexpress/ and Chai from linearmotionbearings /ebay/. BST for sure can provide the double ball nuts , i assume Chai also. No reason to buy 2 single, but depends on the design. On Jonathans build i asked about the spacers spring washers, he pointed from where, so the info should be somewhere there. Their prices are very similar, both do perfect machining, so really its up to you.

To resume various advices for my builds, that i received mainly from Dean and Jonathan , for your size machine
if stepper driven 1:1 with short belts and pulleys on all axis:
-short belt HDT5 15 size, if heavy gantry maybe 25 size, pulleys 20t
-z 1605 screw
-gantry 1610 screw if mainly woodworking for faster speeds ,1605 if mainly aluminum
-long axis 2010 or 2005 respectively, i see no reason to go to 25xx size

the following is my personal understanding:

-gantry supports ~ 30cm/normal/ to 40cm/heavy duty/ spacing of the bearing blocks , this including the blocks-
-gantry , depends on the design, but ~20cm spacing vertical and 25 horisontal i see as minimum./ including bearings./ 30 and 30 will make very strong machine/

PS. Dont be cheap and buy Hiwin or cheaper Chinese square rails not round

Quote:

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Originally Posted by ba99297

Dean i made some corrections according to your advices. I am not sure i understood everything you said ( as my english are not excellent)
Let the photos talk

---

Yes you have it correct but you can afford to make the triangles little smaller to avoid interfering with material, Or shape them to do same thing.

Now regards the Gantry bearing spacing then 300mm for X axis(long axis) and 200-250mm for Y axis will be fine for most work. Like Silyavski says the wider the more stable but the figures I've given I know work fine esp when using profiled linear bearings.

Regards the twinball nuts then I never use twin ballnuts so can't help here and to be honest I don't see the need for a router type machine. They are Ok for a Milling machines that need to hold tight tolerances but in this case I think your just adding extra expense and work, along with extra maintenance for gains that you don't really need or will probably never see due to other weakness in the machine.?

Remember the machine is only good has it's weakest link and at this size then a single ballnut won't be the weak link so any gains won't be fully seen and the gains you'll get from 2 nuts over 1 nut will be very small to start with and I honestly think you won't see any improvement worth the effort or expense.!!

Ballscrew sizes and pitch then

20mm Diameter 10mm pitch for X axis, don't go with 5mm pitch even if aluminium just change the gearing on the pulleys. Don't use 25mm diameter far to large.!
16mm Diameter 10mm pitch for Y axis, don't go with 5mm pitch even if aluminium just change the gearing on the pulleys. Can use 20mm if you like thou won't accelerate quite has fast 16mm but it will still be plenty good enough and that bit less likely to whip.
16mm diameter 5mm pitch for Z axis.

You guys are a treasure
Your advices is for me GOLD
I go on with my plans. I add profiled rails and carriages ( downloaded from hiwin site). Before I go on with my gantry design I would like your opinion about the issues that I will come up with. What are the the points that I have to be careful. This is my progress

Attachment 11122

But I am wondering if the ballscrew sould be placed between the two 80X80 beams of the gantry, in front of Y axis (near z axis ) or in the back of Y axis. I also wonder about the best way to connect Y axis with X axis carriages.
Any idea will be helpful

Vagelis

Quote:

---

Originally Posted by ba99297

But I am wondering if the ballscrew sould be placed between the two 80X80 beams of the gantry, in front of Y axis (near z axis ) or in the back of Y axis. I also wonder about the best way to connect Y axis with X axis carriages.
Any idea will be helpful

Vagelis

---

Hi,
many different schools of thought here. Basically depends on what you aim to achieve, what rigidity you aim for, the overall weight of gantry you will finish with, and how you intend to move this weight, how fast and not at last the money that you can spend on the structure, the motors and the drivers.

To resume it all for the gantry sides: 1 side plate like at the drawings could be ok if you keep the gantry not raised, directly on the sliding plates, if you raise the gantry you will have to do a profile like structure to make it stiff and strong in all directions/ possibly from 10mm thick steel sheet will be best/. There is a calculator in the sticky post for that purpose.

Now to the gantry drawing itself. Have in mind that this is not the voice of experience, i am like you building now my 2 first machines, however i gave it a lot of thought:

The typical:

-Screw at the back will work, many make their machines that way, combined with the rails on top and bottom of the gantry. That is how i designed my first build.
Points to consider: more complicated Z design, rails need more time to be aligned, care should be taken for the Z strength in all directions.

-Screw in the middle. Great design, but most do it from aluminum-plate at the back and plate at the front with channel in the middle. While i like it i did not choose it due to expensive material, my inability to process it at home precisely-cutting, drilling tapping...etc., Beautiful but quite costly. Of course it could be done from steel plate, but then the combined weight. Or ribs here and there at the back, but still without a front plate will not be strong enough to my liking. Plus the plates will protect the ball screw.

-The typical commercial router, rails on the front plate, screw inside, raised gantry. I could not help but post the picture of the Techno, which is a typical example
Attachment 11147

If into woodworking and sheet material ok. But not a multitask one. Man, how i hate that design :toot:. The z could go left right further, so the table could be not so wide, but then the gantry raisers should be strong enough, then the Z travel is very small, so if we want travel of 200mm then the weight, then the motors...etc.

Other:
There are other designs but as they are very purpose specific i would not recommend them.
You could take a look also of my design of gantry on the second machine i am starting to build.I hope will be successful. Its meant for strength and precision for the long gantry, also an ease of implementing, especially epoxy leveling the rails . Just as an idea that you could further develop if you like it http://www.mycncuk.com/forums/router...html#post52573, though more soldering, various sizes profile, heavier.


At the end the design is choosing between the various trade offs for the purpose of what will suite you most.

Hi guys
Quite a long time since my last post
I am thinking about an arrangement for the gantry of my machine
Before i go on with the plans i want your advice about the basic idea
Three 120X60X3mm beams will be welder making a C shape
In front of this "C shape" a 15mm aluminium plate ( blue color) will be bolted in order to bolt on this plate the profiled rails
The plans are not accurate, so any imperfections will be corrected. I just want your opinion in order to see if this arrangement is good or bad an then go on with the way i will attach the gantry on the carriages.
The gantry will be pulled by two Yascawa servos 400 watt and a 2010 ballscrew
Thanks for you time

Vagelis
Attachment 11274Attachment 11275Attachment 11276Attachment 11277Attachment 11278

I like the look of that but it looks weak where it joins the bottom plates. All that weight is hinged off the bottom face of the lower beam. I feel it needs something like this added each end;

Attachment 11279

Eddycurrent thanks for your answer
As i said the plans are not accurate and mostly i want an opinion about the 120X60 box tubes arrangement
If it is ok i will go on with the triangulation support that will attach the C shape gantry to the carriages
To be honest i was thinking something like what you design but a little bit more complex. As what i have in mind will be influenced from the gantry shape, that is why i didn’t design the left and right parts of the gantry
Thank again
Vagelis

Looks Nice!

It would be even better if you could design it so that the motor is inside the gantry. may be with some door plate that bolts to the sides. I assume you will use any way belt from the motor to the screw, not drive it directly?

Silyavski thank for your idea but thiw is not possible as the motor wont fit in the gantry.
I am working now with the plans so i can show to the forum 2-3 different ways to attach the gantry to the carriages.
Thanks for your time

Vagelis

Hi guys here is some progress
Attachment 11300Attachment 11301Attachment 11302Attachment 11303Attachment 11304
My basic question if this arrangement is suitable for such a machine
The green colour is 1,5 cm aluminium and all the others steel.
The rectangular tube is 120X60
At the beginning i was planning to use 3 120X60 rectangular box tubes in order to make a C shape gantry but finally i change the plans
I will also like to hear your opinion about the way i attached vertical pieces of the side parts of the gantry to the horizontal parts
Finally i would like to know if it is better to bolt or to weld the rectangular tubes to the sides of the gantry

Thanks for your time

Vagelis

Hi Vagelis,

Quote:

---

Originally Posted by ba99297

My basic question if this arrangement is suitable for such a machine

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This design will be fine I've use a very similair design on machines but with all aluminium construction.

Quote:

---

Originally Posted by ba99297

I will also like to hear your opinion about the way i attached vertical pieces of the side parts of the gantry to the horizontal parts.
Finally i would like to know if it is better to bolt or to weld the rectangular tubes to the sides of the gantry

---

The arrangement of vertical and horizontal looks ok but with the lower Horizontal base plate you may want to think about how your going to attach to the X axis ballscrews.? It may be better to have the lower plate extend out the side and attach screws to it's under side.?

Regards welding or bolting then NO I wouldnt weld it has you'll have very little room for adjustment. I've said it many times but I'll repeat because it's so important to a Good DIY machine.!!. . . . .ADJUSTMENT ADJUSTMENT ADJUSTMENT . . . . Welding solid is OK for some areas like the frame but for a Gantry then I'd only weld the minimum if at all.!

Also realise because your planning to use Steel for the Gantry sides and base plate it will twist and warp while welding so you'll need to machine the lower face of the Base plate which sits on the Linear bearings. For this reason I wouldn't Use Steel in this area and have Aluminium gantry sides/base plates and bolt together. Still use Steel for the cross beams just bolt it all together.

I would also have 2x brace supports between top & bottom cross beams across the width at the rear. This will help reduce resonance.

Dean how thich aluminium plate do you suggest?
Is 20mm ok or i could go on with 15mm
Firstly i was planning to have all the gantry welded BUT the front plate ( green color at the above photos ) would be 15mm aluminium true leveled.
Also ( as the y axis rails would be at the same plane) i would use two plates to attach the gantry to the carriages . They would be connected each other with bolts ( one bolted on the carriages and the other welded one on the gantrys sides ) so i could adjust the vertical position of the spindle. I will make a plan and i will come back

Some progress so far
Attachment 11470

Attachment 11471


Attachment 11472

Attachment 11473

Attachment 11474




Attachment 11475

Attachment 11476


Attachment 11477



Attachment 11478

Attachment 11479

Attachment 11480

Attachment 11481

Attachment 11482

Attachment 11483

Attachment 11484
The red colour (at the gantry ) is aluminium plate 20mm bolted together
The green gantry plates are also 20mm aluminium plates that will be bolted with the carriages. Under that green plates will be attached the ballscrews
Distance between y axis profiled rails ( centre of rails ) 200mm
Tell me first your comments and i will then ask my questions
Thank for your time

Vagelis

No one out there for any advice?

It definitely looks strong and at the same time good looking. The green plates, they are wider at the back so are you putting the ball nut near the back ? maybe it would be better to have it central or in line with the spindle collet ?

To be honset i think the green plates are a little bit wrong
I must correct the design. I am thinking of make the green plates square and connect the ball nut on the external red aluminium plate that will be designed longer. I dont know if i am understood, so i will design and come back later. Eddycurrent thanks for your answer.

Yes I see what you mean, the red plate must come below the level of the rails to both protect the ball screw and also to allow mounting of the ball screw to the outside of the top beam.
But will there be enough room between the extended red plate and the beam to fit the ball screw in. ?

If you see photo number 13 you will see how much space there is. This space isnt enough to match the ball screw between the plate and the 80X80 box beam. So i could even make the gantry a little bit wider or match the ballscrew at the outer side of the red aluminium plate. My first thougth was to put the X axis ballscrews at the same vertical plane as the profiled rails of x axis. In that case the x axis ballscews would cross the back plate of the aluminium construction that i use to attach the steal beams with the profiled rails. I dont know if this is a good idea as in this case i will have the x and y axi ballscrews been corsed very close each other.

I'd extend the outside gantry plate below the X axis carriages and have the ballnut housing attach to this. You might need to put spacers on the frame for the BK/BF ball screw ends but it shouldn't matter. I've done just this with my design. which you and see here...http://www.mycncuk.com/forums/gantry...planes-12.html that way you can mount the x axis carriages on the bottom 20mm ali plate and not have to bother with the green plates?

Attachment 11497

Some small changes
Attachment 11508

Attachment 11509

Attachment 11510
The green plate(20mm aluminium plate ) will be bolted on the carriages and then i will bolt the green plate with the red plate (20mm aluminium plate)
Could anybody told me what are the critical spots that i must have freedom to adjust. I think is obvious that the spindle should be vertical with the cutting surface. Is this possible to achieved by putting shims between the red and the green aluminium plate.

Vagelis can you show an exploded view or See thru view so that can see how Steel fastens etc. This seems a very complex arrangment of plates that may not be required or adding a lot to overall strength.? The design is correct regards gantry sides Etc just looks more complicated than it needs to be.

I'm also curious to how your arranging the ballscrew/motors because it looks like the steel supports across gantry could clash with ballnut.?

If you prefer Email me Model.

Dean the steel supports are from 120X60 steel tube so they leave 60mm space for the ballnut. I dont know if this is enough but even if it isnot i could make the steel supports from 40X80 tube so 80mm would be the space for the ballnut. Regards how steel fastens i explain. The 120X60 beams will be fist welded like that

Attachment 11537


Then the red assembly (made from 20mm aluminium) will be bolted with the tubes like that
Attachment 11538 Attachment 11539
I dont know if the following picture will help you
Attachment 11540

Anyway i have sent you the model did you get it

Thank for your time

Gantry looking a bit similar to this; but stronger, maybe there's something here for ideas ?
http://www.mycncuk.com/forums/gantry...html#post49880

I believe that this mixing things will not greatly benefit you.

The real things that should be considered are: precision, strength/bend twist/, weight , ball screw length, price.

What i mean is the aluminum will raise the price, lead to lower precision and a lot of hassle in combination with the steel profiles, and possibly raise even the weight. What you will gain is beauty.

I dont know what precision you aim for, but any imprecision in the aluminum will transfer to loss of precision and need to adjust.

So from my limited understanding, either use steel and epoxy or use precisely machined aluminum for all the gantry, like Dean makes his ones.

Aluminum will not magically solve rails alignment as it seems you believe, unless you buy specially intended /$$$/ and precisely machined /$$$ or ability to do it/ .

Combining it with steel will lead to shimming, what you on the first place seem to try to avoid.

If you decide on the steel only machine, i can even help you and arrange all parts laser cut in Bulgaria for cheap, so you can drive 200km and get them, assuming you live in Greece and not very far away. I mean all parts on the machine, like i did from 10mm steel sheet. That can give you immense freedom with the design and extreme ease of assembly. Not to speak of avoiding hours and hours drilling precise holes.

Just for some ideas, you could take a look at my second build. i believe the design of my big machine gantry is even better, avoiding the laser cut parts and aluminum parts as much as possible. And frankly i have not seen a DIY gantry with less overhang. See post 34. You can ignore the extreme Z as there will be 12kg spindle or pneumatic hammer, but take a look how the motor fits, how the gantry sides are avoided to be expensive and heavy. How easy will be to epoxy level the gantry rails as they are in one plane but at the same time there is no overhang at all.

Syliavski thanks for your reply
I am a little bit confused about what materials is should choose for my gantry. Firstly I was planning to make a steel gantry. 120X60 tubes for the gantry welded together lke this
Attachment 11561


Then the sides would be 10mm steel laser cutted.

Attachment 11562
I would even put the green aluminium plate at the front of the gantry, or i would epoxy level the tubes surface so that the rail would be on the same plane.
After that came Dean who adviced me not to have a fully welded gantry so i would be able to adjust. In fact at the above plans i was planning to bolt the sides with the 120X60 beams. Also i was planning to epoxy level tha base plates of the gantry or use shims in order to adjust.
After Deans comments i come up with these plan

Attachment 11563Attachment 11564
with the grey color represent steel and the red color aluminium.
I am really confused about what is better or not. I am starting to make a plan and as i have no experience about the difficulties that i will come up with, i dont know if i am right or if am wrong
So far thanks everybody for your help.

Vagelis

Hi,
my intent was not to confuse you, but to point you that aluminum plates bolted to the steel profile is in no way different than aligning rails to steel gantry. Also that you need to machine it or find somebody to machine it precisely.

You should choose what ever method is easier for you to make or order.

Silyavski i didnt mean that you confuse me ,i just cant decide what is better for the kind of macine i am trying to construct. Steel looks for me a better choice as aluminium will raise the cost

One basic question
If i choose aluminium as the basic material of the gantry, could i have 6-10mm holes laser cutted at a 20mm aluminium plate. They told me that there is a "law" that says that you cant laser cut holes smaller than the thickness of the material. Is that true ? That means if i have a 10mm thickness steel i will have 10mm laser cutted holes, accordingling about aluminium.
Thanks

Vagelis

Quote:

---

Originally Posted by ba99297

One basic question
If i choose aluminium as the basic material of the gantry, could i have 6-10mm holes laser cutted at a 20mm aluminium plate. They told me that there is a "law" that says that you cant laser cut holes smaller than the thickness of the material. Is that true ? That means if i have a 10mm thickness steel i will have 10mm laser cutted holes, accordingling about aluminium.
Thanks

Vagelis

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If the laser cut service told you - its so. In 10mm steel there is no problem to cut 5mm holes. But anyway, they could mark you the holes with the laser, so later you drill them. Normally the laser cut service would have a mill also, so they could drill you the holes, once marked.

So far i understood that i should go even with all steel or all aluminium gantry, as combination of these materials will be a little tricky.
I will ask one more time and if somebody reading the thread i will be glad to hear his opinion. In what directions i must have the ability to adjust
FOr example if i go for all steel gantry, all parts welded and epoxy leveled for y axis rails, also epoxy leveled for the plates that will be bolted on the carriages what are the spots that should not be welded but bolted in order to have the ability to adjust?

After over a month of inactivity i come back. Just one question before upload some resent photos.
For 2010 ballscrew should i use BF/Bk 15 or BF/BK 17 ?

Thanks

Quote:

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Originally Posted by ba99297

For 2010 ballscrew should i use BF/Bk 15 or BF/BK 17 ?

---

BK15 Vagelis.

Hello everybody. I came back to show my little progress.
I want to remind everyone that we are talking about a cnc router with

X 1800mm
Y 1000mm
Z:300mm

It will be moved with 4 ( 2 x axis, 1 Y axis, 1 Z axis ) 400 watt yaskawa servo sigma II.
Steel is the basic material for the construction ( except z axis that I didn’t design yet )
As the table has been discussed many times, I have nothing to say. I just upload two photos . Basic beam is 80X80X4 mm.

Attachment 11947 Attachment 11946

The gantry will be maid from two 120X60 X ( 3mm or 4mm thick steel ). At the end of the gantry frame, 8mm and 10mm steel plates will be welded in order to reinforce the gantry attachment to the side braces that will be bolted on the carriages.
Attachment 11948 Attachment 11949Attachment 11959Attachment 11960




If it will be needed ( I try to avoid it ) the front face and the side (left-right ) faces will be perfectly milled to be vertical each other.

Here I want your opinion about the way I laser cut the steel plate and the way I try to keep everything square in order to avoid (if possible) machining cost. If you notice the plates has been cut in such a way ( like a puzzle ) that it is difficult to distort when I will weld them ( I am planning to tig weld the parts in order to reduce heat distortion). Do you think this trick ( “ puzzle cut “ ) will work ?

Attachment 11950

The same way I made the side braces here are some photos.

Attachment 11951Attachment 11952



If you notice the side braces have straight slots in order to fine tune the gantry so I will be parallel to the cutting surface.

Attachment 11953Attachment 11954Attachment 11961

At the following photo you can see two holes where I will bolt screws that will help me to adjust gantry height.

Attachment 11955

Also the straight slots ( on the vertical piece of the side braces ) will allow small ( up-down ) movements. Side braces and gantry frame will be bolted together.

Attachment 11956

As for the ball screw mounts, they are also adjustable.
Attachment 11957Attachment 11958

I want your comments if you wish , an I remind you my basic questions
Attachment 11962
1. Is the gantry overbuild?
2. Is 10mm steel ( for gantry side braces, front face, and side reinforcing )too much for such a construction or should I go with 8mm 7mm or 6mm. I am asking because if we follow the 1:3 relation between steel and aluminum, 10mm steel equals to 30mm aluminum )
3. Will the puzzle cut technique work?

As for the weight the gantry without the motor that will move y axis and without the ballscrew and of course Z axis, weights nearly 41 kgr ( with 10mm thick steel for the side braces and 8mm steel for the reinforce angles and 4mm 120X60 rectangular beam). If I reduce steel thickness and remove steel from some no critical spots, it is obvious that 41 will be easily reduced to 35 or less.


Thanks for your time

Vagelis

Ps: I will use 1:2 gearing but at the above plans i use 100mm 60 tooth diameter for the ballscrew pulley ( that will give me 1:3 gearing, having in mind that the motor pulley is nearly 3,6mm 20 tooth) in order not to have dimension issues if in the future i want to go with 1:3 gearing.

Forget all the cutouts on the gantry which have been included to reduce its mass. The servos you have a plenty powerful enough to move achieve the required dynamic performance for a gantry several times heavier than what you have designed. If you continue with your plan to use 100mm diameter pulleys then the inertia of just one of those pulleys will be more than the equivalent inertia of all three axes! Decide on the rapid feedrate you want, work out what drive ratio is required, select pulleys, then check that the servo motors are capable of driving it with the required acceleration. It is very simple to calculate, so don't compromise the performance of the system by using very large pulleys when they're almost certainly not required. If you're not sure how to work it out then let me know and I'll show you.

In answer to your direct questions:

1. Depends what you want to do with it, but you seem to be in the right ball park.
2. The consequences of using a lower thickness and having to replace it are far worse than the small increase in cost to use 10mm, so unless you're prepared to calculate it just stick with the thickest you're happy to pay for (presumably 10mm).
3. It looks a bit risky to me - the tolerances on the parts would have to be very good for them to fit together properly.

Jonathan thanks for your responce.
As for the pulleys i am planning to use the following setup

X axis: 2 X 2010 ballscrews 1500mm long with 2:1 gear
Yaxis: 1 x 2010 ballscrews 1000mm long with 2:1 gear
Z axis: 1 x 2005 ballscrews 350mm long with 2:1 gear

As for the speed calculations i have made this thread

http://www.mycncuk.com/forums/gantry...culations.html

So with 2010 ballscrew and 2:1 gear ratio

i will have

motor gear ratio 1
ballscrew gear ratio 2
ballscrew length 1500
ballscrew diameter 20
ballscrew pitch 10
ballscrew rpm 1500
ballscrew rpm threshold ~1200
rapids mm 15000


Vagelis